Carburetor



H. O. HEGNA Oct. 9, 1962 CARBURETOR Filed March 3l, 1960 FIG.1O

INVENTOR N .z

0L, HEGNA Aromvs United tates Patent 3,057,606 CARBURETOR Hans OlavHegna, Sausalito, Calif., assignor to California Research Corporation,San Francisco, Calif., a corporation of Delaware Filed Mar. 31, 1960,Ser. No. 19,017 2 Claims. (Cl. 261-65) This invention relates tocarburetors for internal combustion engines and more particularly to anovel throttle Valve for alleviating some of the diflicultiesencountered under climatic conditions which cause icing in thecarburetor.

In cool, humid weather the evaporation of a volatile fuel from theair-fuel mixture passing through the carburetor drops the temperature ofthe mixture below the freezing point of the entrained water vapor. Underthese conditions, the water vapor condenses out of the air and forms icydeposits on the chilled internal portions of the carburetor. Of primaryinterest to the present invention are those icy deposits which build upon the throttle valve and cause the engine to malfunction or stallduring the warming-up period.

Experience in cold-weather driving of automobiles under icy conditionshas shown an inclination of the engine to stall if it is placed in anidling condition during the warm-up period. Thus, the engine may falteror stall when traffic conditions require that the automobile be broughtto a stop. The constant restarting of the engine, which may in itself'oe difficult, creates a situation which is at least inconvenient forthe driver and which is not conducive to the desirable steady iiow oftraiiic.

A principal object of this invention is to provide a i novel throttlevalve for a carburetor, which throttle valve will reduce the tendency ofan engine to malfunction when operated under conditions which cause icydeposits .to form in the carburetor.

Another object of this invention is to provide a carburetor which willfunction to reduce the tendencyof an engine to stall during the warm-upperiod while operated under varying loads in cold weather.

Other objects of this invention will become apparent as the descriptionof it proceeds hereinafter, in conjunction with the accompanyingdrawings in which:

FIG. l illustrates in side elevation and partly in section a carburetorin which this invention is incorporated.

FIG. 2 is a plan view of a throttle valve made in accordance to thisinvention.

FIG. 3 is a View in side elevation and partly in section taken along theline 3-3 of FIG. 2.

FIG. 4 is a view in side elevation and partly in section of amodification of a throttle valve made in accordance with this invention.

FIGS. 5, 7 and 9 illustrate in plan view three other, differentmodifications of throttle valves embodying this invention, and thecorresponding FIGS. 6, 8 and l0, which are taken respectively along theline 6-6 of FIG. 5, the line 8-8 of FIG. 7, and the line 10-10 of FIG.9, illustrate transverse sections of the corresponding modiiications ofthrottle valves embodying this invention.

FIG. l illustrates an exemplary carburetor 20 in which the throttlevalve of this invention has been installed. As will be appreciated inthe art, in a carburetor of the type illustrated air is drawn into thecarburetor through the air horn 22 and iiows past the open choke valve24 and through the auxiliary Venturi tube 26 and the main Venturipassage 2S and thence through the mixture conduit 30. When the throttlevalve 32 is open, the air flows through the auxiliary Venturi tube withsufficient velocity to reduce the pressure at the opening 34, within ythe throat of the auxiliary Venturi tube, of the main discharge jet 36.The reduced pressure causes fuel to flow from the iioat chamber 38,which is vented through the vent tube 40 to the air entering thecarburetor, and through the main discharge jet and into the air streampassing through the auxiliary Venturi tube. The fuel is entrained in theair, and as the mixture iiows toward the mixture conduit 30 it mergeswith the air owing through the main Venturi passage to achieve thedesired ratio of fuel to air necessary for the proper operation of theengine to which the carburetor is attached.

The throttle valve 32 is a plate pivotally mounted within and settransversely across the mixture conduit. The valve can be rotated by alinkage outside of the carburetor body to control the opening of themixture conduit from a position of the throttle valve where the conduitis substantially closed to the passage of air through it, as indicatedby the solid line drawing of the throttle valve in FIG. 1, to a positionwhere the mixture conduit is substantially fully open for the passage ofthe mixture through it, as indicated by the dotted line drawing of thethrottle valve 32 in FIG. l. When the throttle valve is open, themixture of fuel and air passes from the carburetor into the intakesystem of the engine. When the throttle valve is closed, the volume ofair passing through the carburetor is at a minimum, and the velocity ofthe air through the auxiliary Venturi tube is too low to producesufficient reduction of pressure within the throat of the auxiliaryVenturi tube to cause fuel to flow from the main discharge jet.

When the throttle valve is in the closed, or idle, position, theoperation of the engine causes the pressure to be reduced in the portion42 of the mixture conduit below the throttle valve. The air in the upperportion of the carburetor is at substantially atmospheric pressure, andthis pressure, acting through the idle-air bleed or bypass 44 andthrough the idle tube 46, forces fuel through the idle port 48 into themixture conduit below the throttle valve. 'Ihe secondary idle air bleed50 assists this operation. Some air is entrained with the fuel ejectedfrom the idle port, and additional air iiows through a small clearance52 between the throttle valve periphery and the inner wall of themixture conduit to form the proper air-fuel ratio for operation of theidling engine.

A second idle port 54 opens just above the throttle valve. When thethrottle valve is slightly rotated from its closed position, the airpassing around its periphery reduces the pressure at the second idleport, and fuel flows from the latter in addition to the fuel flowingfrom the first idle port 48 to maintain the proper ratio of fuel in theincreased volume of air. When the throttle valve is opened still more,the increased air flow through the carburetor balances the pressuresbetween the idle air bleed and the idle discharge ports, and fuel ceasesto flow from the latter. At the same time, the iiow of air through theauxiliary Venturi tube increases sufficiently to cause fuel to bedischarged from the main discharge jet in the proper air-fuel ratio forthe desired engine operation.

In certain cold-weather conditions malfunctioning of the carburetor isexperienced, caused by icy deposits formed on the internal parts of thecarburetor. It has been determined that these icy deposits form mostreadily on cool days of relatively high humidity, and they have beenexperienced in a range of ambient temperatures from about 25 F. to about60 F. when the relative humidity was above about 60%, the icingcondition increasing in severity as the relative humidity increased. Thetemperature range between 30 F. and 50 F. appears to be especiallycritical for icing conditions. In a series of tests made on automobilesto determine the conditions which would cause carburetor malfunctioningdue to icing, it was found that at an ambient temperature of 40 F. with100% relative humidity, 43% of the test cars experienced stalling one ormore times during the warming-up period.

Insofar as carburetor operation is concerned, icy deposits areparticularly critical when they build up in the Venturi passages and onthe throttle valve. Icing of the throttle valve produces erratic anduneven operation of the engine and stalling, particularly when theengine is placed in an idling condition during the period it is warmingup. A suggested cause for this malfunctioning is that the ice depositedon the throttle valve while the engine is running with the throttlevalve open tends to melt olf of the surface of the valve when the latteris placed in the idle position where it is no longer cooled by largevolumes of refrigerated air passing over it. The throttle valve picks upheat from the engine, and the ice adhering to it melts at the surface ofthe valve, producing a lm of water upon which the icy particles abovethe surface layer oat. The icy deposit then will slide toward the lowestside of the throttle valve and block the small air passage between theperiphery of the throttle valve and the inner wall of the mixtureconduit, thus cutting off a large portion of the relatively small amountof air which flows around the throttle valve in the idle position. Insome cases, the icy particles which bridge the peripheral clearancebetween the throttle and the wall of the mixture conduit apparentlyrefreeze together, caused perhaps either by coming into contact with thecold Wall of the body of the carburetor or by being more directlyexposed to the stream of cold air which is attempting to flow throughthis clearance.

The throttle valve is normally set to have a clearance in the range ofabout ve-thousandths to about fivehundredths of an inch between itsperiphery and the adjacent wall of the mixture conduit when it is in anidle position, the clearance depending upon the construction of theparticular carburetor, to provide the proper amount of air to mix `withthe fuel issuing from the idle port for the operation of the idlingengine. In the idle position, the amount of air flowing past thethrottle valve does not appreciably affect the amount of fuel issuing`from the idle port, the latter remaining substantially constant. Hence,when an appreciable portion of this air supply is cut oli", the ratio ofair to fuel in the mixture Agoing to the engine is changed drastically,and the engine no longer operates properly.

The present invention improves appreciably the operation of an engineduring the warming-up period. It provides a means for preventing icydeposits from sliding off the surface of the throttle valve and blockingthe air passage around the periphery of this valve when it is in theidle position.

FIGS. 2 and 3 illustrate a preferred embodiment of a throttle valve madein accordance with this invention. In this instance the valve comprisesa circular thin plate or disk 56 which is affixed by the screws 58 to ashaft 60. The shaft may be mounted transversely across and within themixture conduit of the carburetor in a manner to permit the valve to berotated from a closed or idle position to an open or running position.Normally in the type of carburetor illustrated, when the throttle valveis in the closed position it will be tilted at an angle to thehorizontal in a direction transverse to the axis of t-he shaft 60, asshown by the position of the valve 32 in FIG. l. The disk 56 is formedwith, or has securely affixed to it, an upwardly projecting rim portion62 which extends throughout approximately one-half of its periphery onthe portion of the disk which will be in the lowermost position when thevalve is installed in an operating carburetor. The rim portion has asmall gap 64 formed through it at its mid point to permit water producedfrom the ice melting on the surface of the valve to drain away. The rim62 prevents icy deposits from sliding over the edge 66 of thisperipheral portion of the `disk and blocking the air passage 52 betweenit and the wall of the mixture conduit. The gap 64 prevents suicientwater from accumulating to oat the icy deposits over the top of the rim62 and blocking this air passage.

A throttle valve made in accordance with the illustrations of FIGS. 2and 3 was installed in a carburetor on an engine which was operated inalternate cycles of l5 seconds idle at 800 r.p.m. and l5 seconds runningat 2300 r.p.m. continuously for 30 minutes. rI`he cycling operation wasdone automatically by mechanical means to maintain uniform 15-secondintervals and to insure a uniformly repetitive engine control for eachconsecutive condition. The air fed to the carburetor had a temperatureof 45 F. and a relative humidity of An icing condition occurred in thecarburetor.

The total number of revolutions made by the engine during the idlingcycles only was used as a gauge of dependability of engine operationduring the period, since this would reect not only stalling but alsofaltering or slowing-down of the engine or other malfunctioning whichdid not result in a complete stall. When the engine stalled in al5second id'ing period, it was started automatically by the cyclingmechanism at the beginning of the next consecutive running cycle.

The throttle valve of this invention was tested under the same operatingconditions against the standard flatdisk throttle valve supplied withthe carburetor being used, each throttle valve being used in the samecarburetor on the same engine for the different tests. With the throttlevalve of the present invention, the engine accumulated 9,952 totalrevolutions during the id'ing periods of a 30-minute run, while with thestandard throttle valve supplied with the carburetor the engineaccumulated a total of 3,788 revolutions during this period. Theoperation of the engine under the stated test conlitions was notentirely trouble free during the idling cycles when the throttle valveof this invention was used in the carburetor. However, its operation wasvery detinitely improved over that which obtained when the stendardthrottle valve was used. Separate, similar tests substantiated thebeneficial effect of the throttle valve of this invention.

FIG. 4 illustrates in sectional view another embodiment of thisinvention. In this embodiment, a separate circular plate 68 is used,made with an upturned peripheral rim 70 completely around itscircumference. Two diametrically opposed gaps 72 and 74 are formed inthe rim, similar to the gaps 64 of FIG. 2. The plate 68 is secured onthe upper face of a standard throttle valve disk 76 by means of thescrews 78 which fasten the disk to the shaft 80. This auxiliary platefunct'ons in the manner of the rim 62 described heretofore with respectto the first embodiment of the invention to restrain icy deposits fromsliding over the peripheral edge of the throttle valve and blocking thesmall air passage between it and the wall of the mixture conduit 30 whenthe throttle valve is in the idle position. The plate is symmetricallyformed, and hence does not require a determination as to which side ofthe rim belongs in the uppermost position and which in the lowermost tofunction properly when placed on a throttle valve of the formillustrated. The full rim functions to prevent the migration of icydeposits from the face of the throttle valve over any portion of itsperipheral edge.

In the embodiment of the invention illustrated in FIGS. 5 and 6, anauxiliary member 82 of corrugated form is applied to the uppermostsurface of the throtte valve disk 84. The corrugations are disposed inalignment with the axis of the shaft 86 and preferably are made with thevertically disposed faces 88 at steep angles to the plane of the upperface of the throttle valve disk. The corrugations function to preventthe icy deposits from sliding on the face of the throttle valve towardthe side which is lowermost when the valve is in the idle position. Itwill be understood that the throttle valve disk itself may be corrugatedto perform the same function as the auxliiary plate 82 performs.

In the embodiment of the invention illustrated in FIGS. 7 and 8, thedisk 90 of the throttle valve plate is formed with, or has aiiixed toit, a plurality of projections 92 which extend upwardly from itssurface. These projections may, for example, be pins secured in holesdrilled into the plate and placed sutlciently close together to preventicy deposits from sliding off of the surface of the plate in masseslarge enough to block the clearance between the throttle valve and thewall of the mixture conduit when the throttle valve is in the idleposition. Alternatively, an auxiliary flat member having closely yspacedprojections extending upwardly from it may be secured on the surface ofthe standard throttle valve plate to achieve this result.

FIGS. 9 and 10 illustrate a different embodiment of the invention. Inthis embodiment, a piece of at screenlike material 94 is Shaped toconform wit-h the valve plate 96 and is secured by the screws 98 toclose contact with the surface of the plate exposed to icy deposits. Thescreen preferably is made of interwoven metal wires land with a imeshsufficiently coarse to cause the frozen water deposited from thefuel-air mixture to be trapped initially in the interstices of theScreen, which will prevent the icy deposits from sliding oi the surfaceof the throttle valve when the latter is in the idle position. In thisembodiment of the invention, as well as in all of the other embodimentspreviously described, the Water formed `by the ice melting on thethrottle valve is permitted to drain olf of the valve and be drawn intothe intake system of the engine.

IWhen the throttle valve is open to operate the engine substantiallyabove its idling speed, there is suflicient clearance between theperiphery of the throttle valve and the inner wall of the mixtureconduit to permit the icy deposits to fall, or be drawn into, the intakesystem of the engine without blocking the air passages necessary forproper engine operation. The ice melts, of course, in the intake systemas the engine warms up, and the resultant water is converted to vapor,which is entrained in the fuel-air mixture and passes through the enginewithout causing the engine to malfunction.

The several embodiments of the invention described heretofore andillustrated in the drawings Present an effective means for preventingice accumulations on the throttle valve lfrom causing malfunctioning ofthe engine during the idle period. It will be apparent that theinvention can be embodied in other forms than those presented herein andapplied to other shapes of valve plates than the disk of the exemplaryembodiment without departing from the inventive concept. Therefore, itis intended that the invention embrace all equivalents within the scopeof the appended claims, v

I claim:

1. In a carburetor, a conduit for entraining a mixture of fuel and air,a throttle valve in said conduit comprising a plate pivotally mountedtransversely of said oonduit and rotatable from a rst positionsubstantially but not entirely `closing said conduit to the passage ofair therethrough to a second position in which said conduit issubstantially opened to the passage of said mixture therethrough,ice-holding means `on a surface of said plate and `distributed over asu-btantial portion of the area of said surface to restrain icedeposited on said surface during passage of said mixture through `saidconduit from sliding off said surface in pieces large enough t0substantially completely :close off at least a portion of said conduitto the passage of air therethrough when said plate is in approximatelysaid first posit-ion, said ice-holding means comprising corrugations onsaid surface, said corrugations positioned in substantially parallelalignment with the axis of rotation of said plate.

2. In a carburetor, a conduit for entraining a -mixture of fuel and air,a throttle valve in said conduit comprising 'a plate pivotally mountedtransversely of said conduit and rotatable from a tirst positionsubstantially but not entirely closing said conduit to the passage ofair therethrough to a second position in which said conduit issubstantially opened to the passage of said mixture therethrough,ice-holding means on a surface of said plate and distributed over asubstantial portion of the area of said surface to restrain icedeposited on said surface during passage of said mixture through saidconduit from sliding olf said surface in pieces large enough to`substantially completely close olf at least ya portion of said conduitto the passage of air therethrough when said plate is in approximatelysaid first position, said ice-holding means comprising an element ofscreenlike material secured to said surface and in contact therewith.

References Cited in the file of this patent UNITED STATES PATENTS1,495,696 Kinnie et al. May 27, 1924 1,633,050 T-horton June 2l, 19271,753,009 Hess Apr. l, 1930 1,882,966 Schaffner Oct. 18, 1932 2,328,736Mock Sept. 7, 1943 2,393,760 Eberhardt Ian. 29, 1946 2,658,734 HenningNov. 10, 1953 FOREIGN PATENTS 182,924 Great Britain July l2, 1922507,977 Great Britain June 23, 1939

